A judge's decision granting B.C. teachers the right to negotiate class size has given their union a distinct advantage in ongoing contract talks and could cost the government hundreds of millions of dollars.

The B.C. Supreme Court ruled Wednesday that a 2002 law banning talk of class size from contract negotiations was unconstitutional, and gave the government a year to get rid of it.

The B.C. Teachers' Federation is in the middle of negotiating a new collective agreement, and labour experts say the ruling gives the union serious leverage.

"I would imagine that Christy Clark is going to have to run an election fairly soon, and that she will not want a major confrontation with the teachers, and that they're going to know that, so I think this is going to be tough bargaining for the government," said Marjorie Griffin Cohen, a professor of public policy at Simon Fraser University.

"I think they will have to give in on class size and composition."

If class sizes are rolled back to 2002, the necessary funding increase is estimated to be in the hundreds of millions -- if not billions -- of dollars.

"It will take money. It will take significant amounts of money," BCTF President Susan Lambert told CTV News.

She added that she's looking forward to hearing from the premier about how she plans to resolve the problems in the legislation.

"What I want to hear is my phone ringing. I want to hear a meeting. I want to be sitting at a table," Lambert said.

On Wednesday, Clark said it was too soon to tell if class size and composition will be allowed back on the bargaining table.

"I will have to have a look at the entirety of the judgment. The court has given the government a year to respond to it and to make the changes," she said, adding that she'd like to see the issue resolved quickly.

With a report from CTV British Columbia's Rob Brown